libatalk/util/server_child.c

   1 /*
   2  * Copyright (c) 1997 Adrian Sun (asun@zoology.washington.edu)
   3  * Copyright (c) 2013 Frank Lahm <franklahm@gmail.com
   4  * All rights reserved. See COPYRIGHT.
   5  *
   6  * handle inserting, removing, and freeing of children.
   7  * this does it via a hash table. it incurs some overhead over
   8  * a linear append/remove in total removal and kills, but it makes
   9  * single-entry removals a fast operation. as total removals occur during
  10  * child initialization and kills during server shutdown, this is
  11  * probably a win for a lot of connections and unimportant for a small
  12  * number of connections.
  13  */
  14
  15 #ifdef HAVE_CONFIG_H
  16 #include "config.h"
  17 #endif /* HAVE_CONFIG_H */
  18
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <unistd.h>
  22 #include <signal.h>
  23 #include <errno.h>
  24 #include <sys/types.h>
  25 #include <sys/wait.h>
  26 #include <sys/time.h>
  27 #include <pthread.h>
  28
  29 #include <atalk/logger.h>
  30 #include <atalk/errchk.h>
  31 #include <atalk/util.h>
  32 #include <atalk/server_child.h>
  33
  34 #ifndef WEXITSTATUS
  35 #define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
  36 #endif /* ! WEXITSTATUS */
  37 #ifndef WIFEXITED
  38 #define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
  39 #endif /* ! WIFEXITED */
  40 #ifndef WIFSTOPPED
  41 #define WIFSTOPPED(status) (((status) & 0xff) == 0x7f)
  42 #endif
  43 #ifndef WIFSIGNALED
  44 #define WIFSIGNALED(status) (!WIFSTOPPED(status) && !WIFEXITED(status))
  45 #endif
  46 #ifndef WTERMSIG
  47 #define WTERMSIG(status)      ((status) & 0x7f)
  48 #endif
  49
  50 /* hash/child functions: hash OR's pid */
  51 #define HASH(i) ((((i) >> 8) ^ (i)) & (CHILD_HASHSIZE - 1))
  52
  53 static inline void hash_child(afp_child_t **htable, afp_child_t *child)
  54 {
  55     afp_child_t **table;
  56
  57     table = &htable[HASH(child->afpch_pid)];
  58     if ((child->afpch_next = *table) != NULL)
  59         (*table)->afpch_prevp = &child->afpch_next;
  60     *table = child;
  61     child->afpch_prevp = table;
  62 }
  63
  64 static inline void unhash_child(afp_child_t *child)
  65 {
  66     if (child->afpch_prevp) {
  67         if (child->afpch_next)
  68             child->afpch_next->afpch_prevp = child->afpch_prevp;
  69         *(child->afpch_prevp) = child->afpch_next;
  70     }
  71 }
  72
  73 afp_child_t *server_child_resolve(server_child_t *childs, id_t pid)
  74 {
  75     afp_child_t *child;
  76
  77     for (child = childs->servch_table[HASH(pid)]; child; child = child->afpch_next) {
  78         if (child->afpch_pid == pid)
  79             break;
  80     }
  81
  82     return child;
  83 }
  84
  85 /* initialize server_child structure */
  86 server_child_t *server_child_alloc(int connections)
  87 {
  88     server_child_t *children;
  89
  90     if (!(children = (server_child_t *)calloc(1, sizeof(server_child_t))))
  91         return NULL;
  92
  93     children->servch_nsessions = connections;
  94     pthread_mutex_init(&children->servch_lock, NULL);
  95     return children;
  96 }
  97
  98 /*!
  99  * add a child
 100  * @return pointer to struct server_child_data on success, NULL on error
 101  */
 102 afp_child_t *server_child_add(server_child_t *children, pid_t pid, int ipc_fd)
 103 {
 104     afp_child_t *child = NULL;
 105
 106     pthread_mutex_lock(&children->servch_lock);
 107
 108     /* it's possible that the child could have already died before the
 109      * pthread_sigmask. we need to check for this. */
 110     if (kill(pid, 0) < 0) {
 111         LOG(log_error, logtype_default, "server_child_add: no such process pid [%d]", pid);
 112         goto exit;
 113     }
 114
 115     /* if we already have an entry. just return. */
 116     if ((child = server_child_resolve(children, pid)))
 117         goto exit;
 118
 119     if ((child = calloc(1, sizeof(afp_child_t))) == NULL)
 120         goto exit;
 121
 122     child->afpch_pid = pid;
 123     child->afpch_ipc_fd = ipc_fd;
 124     child->afpch_logintime = time(NULL);
 125
 126     hash_child(children->servch_table, child);
 127     children->servch_count++;
 128
 129 exit:
 130     pthread_mutex_unlock(&children->servch_lock);
 131     return child;
 132 }
 133
 134 /* remove a child and free it */
 135 int server_child_remove(server_child_t *children, pid_t pid)
 136 {
 137     int fd;
 138     afp_child_t *child;
 139
 140     if (!(child = server_child_resolve(children, pid)))
 141         return -1;
 142
 143     pthread_mutex_lock(&children->servch_lock);
 144
 145     unhash_child(child);
 146     if (child->afpch_clientid) {
 147         free(child->afpch_clientid);
 148         child->afpch_clientid = NULL;
 149     }
 150
 151     /* In main:child_handler() we need the fd in order to remove it from the pollfd set */
 152     fd = child->afpch_ipc_fd;
 153     if (fd != -1)
 154         close(fd);
 155
 156     free(child);
 157     children->servch_count--;
 158
 159     pthread_mutex_unlock(&children->servch_lock);
 160
 161     return fd;
 162 }
 163
 164 /* free everything: by using a hash table, this increases the cost of
 165  * this part over a linked list by the size of the hash table */
 166 void server_child_free(server_child_t *children)
 167 {
 168     afp_child_t *child, *tmp;
 169     int j;
 170
 171     for (j = 0; j < CHILD_HASHSIZE; j++) {
 172         child = children->servch_table[j]; /* start at the beginning */
 173         while (child) {
 174             tmp = child->afpch_next;
 175             close(child->afpch_ipc_fd);
 176             if (child->afpch_clientid)
 177                 free(child->afpch_clientid);
 178             if (child->afpch_volumes)
 179                 free(child->afpch_volumes);
 180             free(child);
 181             child = tmp;
 182         }
 183     }
 184
 185     free(children);
 186 }
 187
 188 /* send signal to all child processes */
 189 void server_child_kill(server_child_t *children, int sig)
 190 {
 191     afp_child_t *child, *tmp;
 192     int i;
 193
 194     for (i = 0; i < CHILD_HASHSIZE; i++) {
 195         child = children->servch_table[i];
 196         while (child) {
 197             tmp = child->afpch_next;
 198             kill(child->afpch_pid, sig);
 199             child = tmp;
 200         }
 201     }
 202 }
 203
 204 /* send kill to a child processes */
 205 static int kill_child(afp_child_t *child)
 206 {
 207     if (!child->afpch_killed) {
 208         kill(child->afpch_pid, SIGTERM);
 209         /* we don't wait because there's no guarantee that we can really kill it */
 210         child->afpch_killed = 1;
 211         return 1;
 212     } else {
 213         LOG(log_info, logtype_default, "Unresponsive child[%d], sending SIGKILL", child->afpch_pid);
 214         kill(child->afpch_pid, SIGKILL);
 215     }
 216     return 1;
 217 }
 218
 219 /*!
 220  * Try to find an old session and pass socket
 221  * @returns -1 on error, 0 if no matching session was found, 1 if session was found and socket passed
 222  */
 223 int server_child_transfer_session(server_child_t *children,
 224                                   pid_t pid,
 225                                   uid_t uid,
 226                                   int afp_socket,
 227                                   uint16_t DSI_requestID)
 228 {
 229     EC_INIT;
 230     afp_child_t *child;
 231
 232     if ((child = server_child_resolve(children, pid)) == NULL) {
 233         LOG(log_note, logtype_default, "Reconnect: no child[%u]", pid);
 234         if (kill(pid, 0) == 0) {
 235             LOG(log_note, logtype_default, "Reconnect: terminating old session[%u]", pid);
 236             kill(pid, SIGTERM);
 237             sleep(2);
 238             if (kill(pid, 0) == 0) {
 239                 LOG(log_error, logtype_default, "Reconnect: killing old session[%u]", pid);
 240                 kill(pid, SIGKILL);
 241                 sleep(2);
 242             }
 243         }
 244         return 0;
 245     }
 246
 247     if (!child->afpch_valid) {
 248         /* hmm, client 'guess' the pid, rogue? */
 249         LOG(log_error, logtype_default, "Reconnect: invalidated child[%u]", pid);
 250         return 0;
 251     } else if (child->afpch_uid != uid) {
 252         LOG(log_error, logtype_default, "Reconnect: child[%u] not the same user", pid);
 253         return 0;
 254     }
 255
 256     LOG(log_note, logtype_default, "Reconnect: transfering session to child[%u]", pid);
 257
 258     if (writet(child->afpch_ipc_fd, &DSI_requestID, 2, 0, 2) != 2) {
 259         LOG(log_error, logtype_default, "Reconnect: error sending DSI id to child[%u]", pid);
 260         EC_STATUS(-1);
 261         goto EC_CLEANUP;
 262     }
 263     EC_ZERO_LOG(send_fd(child->afpch_ipc_fd, afp_socket));
 264     EC_ZERO_LOG(kill(pid, SIGURG));
 265
 266     EC_STATUS(1);
 267
 268 EC_CLEANUP:
 269     EC_EXIT;
 270 }
 271
 272
 273 /* see if there is a process for the same mac     */
 274 /* if the times don't match mac has been rebooted */
 275 void server_child_kill_one_by_id(server_child_t *children, pid_t pid,
 276                                  uid_t uid, uint32_t idlen, char *id, uint32_t boottime)
 277 {
 278     afp_child_t *child, *tmp;
 279     int i;
 280
 281     pthread_mutex_lock(&children->servch_lock);
 282
 283     for (i = 0; i < CHILD_HASHSIZE; i++) {
 284         child = children->servch_table[i];
 285         while (child) {
 286             tmp = child->afpch_next;
 287             if (child->afpch_pid != pid) {
 288                 if (child->afpch_idlen == idlen && memcmp(child->afpch_clientid, id, idlen) == 0) {
 289                     if ( child->afpch_boottime != boottime ) {
 290                         /* Client rebooted */
 291                         if (uid == child->afpch_uid) {
 292                             kill_child(child);
 293                             LOG(log_warning, logtype_default,
 294                                 "Terminated disconnected child[%u], client rebooted.",
 295                                 child->afpch_pid);
 296                         } else {
 297                             LOG(log_warning, logtype_default,
 298                                 "Session with different pid[%u]", child->afpch_pid);
 299                         }
 300                     } else {
 301                         /* One client with multiple sessions */
 302                         LOG(log_debug, logtype_default,
 303                             "Found another session[%u] for client[%u]", child->afpch_pid, pid);
 304                     }
 305                 }
 306             } else {
 307                 /* update childs own slot */
 308                 child->afpch_boottime = boottime;
 309                 if (child->afpch_clientid)
 310                     free(child->afpch_clientid);
 311                 LOG(log_debug, logtype_default, "Setting client ID for %u", child->afpch_pid);
 312                 child->afpch_uid = uid;
 313                 child->afpch_valid = 1;
 314                 child->afpch_idlen = idlen;
 315                 child->afpch_clientid = id;
 316             }
 317             child = tmp;
 318         }
 319     }
 320
 321     pthread_mutex_unlock(&children->servch_lock);
 322 }
 323
 324 /* ---------------------------
 325  * reset children signals
 326  */
 327 void server_reset_signal(void)
 328 {
 329     struct sigaction    sv;
 330     sigset_t            sigs;
 331     const struct itimerval none = {{0, 0}, {0, 0}};
 332
 333     setitimer(ITIMER_REAL, &none, NULL);
 334     memset(&sv, 0, sizeof(sv));
 335     sv.sa_handler =  SIG_DFL;
 336     sigemptyset( &sv.sa_mask );
 337
 338     sigaction(SIGALRM, &sv, NULL );
 339     sigaction(SIGHUP,  &sv, NULL );
 340     sigaction(SIGTERM, &sv, NULL );
 341     sigaction(SIGUSR1, &sv, NULL );
 342     sigaction(SIGCHLD, &sv, NULL );
 343
 344     sigemptyset(&sigs);
 345     sigaddset(&sigs, SIGALRM);
 346     sigaddset(&sigs, SIGHUP);
 347     sigaddset(&sigs, SIGUSR1);
 348     sigaddset(&sigs, SIGCHLD);
 349     pthread_sigmask(SIG_UNBLOCK, &sigs, NULL);
 350
 351 }